Skull Radiographic Views & Anatomy

Question 1

What are the main types of skull radiographs

Answer 1

Occipitomental

Postero-anterior mandible

Reverse Towne’s

True lateral skull

Question 2

What are the indications for a occipitomental radiograph

Answer 2

Fractures of the midface
- Le fort I,II, III
-Zygomatic complex
-Naso ethmoidal comples
-Orbital blow out

Coronoid process fractures

Question 3

What are the indications for a postero-anterior mandible radiograph

Answer 3

Fractures of the posterior mandible excluding the condyles

Lesions and fractures involving
-Posterior third of body
- Angles
-Rami
-Low condylar necks

Mandibular hypo/hyperplasia

Question 4

What are the indications for a reverse townes radiograph

Answer 4

High fractures of condylar necks

Intracapsular fractures of TMJ

Condylar hypoplasia/hyperplasia

Question 5

What receptors are used for these skull radiographs

Answer 5

Digital & large enough to capture relevant areas

Question 6

What refrence line is used for patient positioning in most skull radiographs

Answer 6

Orbitomeatal line (canthomeatal line or radiographic basic)

Question 7

What land marks makes the orbitomeatal line

Answer 7

Outer canthus of eye

Centre of external auditory meatus

Question 8

What do OM radiographs show and at what angles can they be taken at

Answer 8

Show facial skeleton, avoiding superimposition of skull base

Can be taken at different angles e.g. 0°, 10°, 30° or 40°

Question 9

With a OM radiograph how many would you take

Answer 9

Typically use 2 together at different angles to evaluate facial trauma e.g. 10° & 40°

Question 10

What position would you want the patient in for a OM radiograph

Answer 10

facing receptor Head tipped back so orbitomeatal line is 45° to receptor

Question 11

What do PA mandible radiogrpahs look at and what is it not suitable for

Answer 11

Shows posterior parts of mandible

Not suitable for viewing facial skeleton because of
superimposition of base of skull & nasal bones

Question 12

What position would you want the patient in for a PA mandible radiograph

Answer 12

Face towards receptor and head tipped down so orbitomeatal line is perpendicular to the receptor (& parrallel to floor if standing)

Question 13

Where does the X-ray beam go in as PA mandible radiograph

Answer 13

Passes through Perpendicular to receptor & centred through
cervical spine at level of rami

Question 14

In the OM & Pa mandible radiogrpahs why is the X-ray beam projected from posterior side

Answer 14

Reduce magnification of face (Since closer to receptor)
-Less distortion of relevant structures
-Back of skull will be magnified more as a result but is less important

Reduce effective dose
-X-ray beam partly attenuated by back of skull before reaching face
-Lower radiation dose to radiosensitive tissues (e.g. lens of eye)

Question 15

What does the reverse townes radiograph look at

Answer 15

Shows condylar heads & necks

Question 16

What position would you want the patient in for a reverse townes radiograph

Answer 16

Face towards receptor with head tipped forward so orbitomeatal line perpendicular to receptor (& parallel to floor if standing)

Roughly a “forehead-nose” position

Mouth open so condylar heads moves out of glenoid fossa

Question 17

Where does the X-ray beam come from in a reverse townes radiograph

Answer 17

30° below perpendicular line to receptor &
centred through condyles